U.S. patent application number 10/275640 was filed with the patent office on 2003-09-18 for acoustic transmission connection, headset with acoustic transmission connection, and uses of the acoustic transmission connection.
Invention is credited to Groth, Toben, Moller, Peter.
Application Number | 20030173145 10/275640 |
Document ID | / |
Family ID | 8159516 |
Filed Date | 2003-09-18 |
United States Patent
Application |
20030173145 |
Kind Code |
A1 |
Groth, Toben ; et
al. |
September 18, 2003 |
Acoustic transmission connection, headset with acoustic
transmission connection, and uses of the acoustic transmission
connection
Abstract
An acoustic transmission connection, e.g. for a headset (13),
comprises a sound tube (2) through which speech signals can be
transmitted from a first end (16) to a transducer, e.g. a
microphone, in a housing or a housing part (3) of the headset. In
the sound tube (2) and in the housing part (3), means are provided
for acoustic impedance matching and possibly means for achieving
acoustic directivity.
Inventors: |
Groth, Toben; (Allerod,
DK) ; Moller, Peter; (Kokkedal, DK) |
Correspondence
Address: |
ALTERA LAW GROUP, LLC
6500 CITY WEST PARKWAY
SUITE 100
MINNEAPOLIS
MN
55344-7704
US
|
Family ID: |
8159516 |
Appl. No.: |
10/275640 |
Filed: |
May 12, 2003 |
PCT Filed: |
May 1, 2001 |
PCT NO: |
PCT/DK01/00295 |
Current U.S.
Class: |
181/153 ;
181/199; 381/338 |
Current CPC
Class: |
H04R 1/342 20130101;
H04R 1/083 20130101; H04R 1/1058 20130101 |
Class at
Publication: |
181/153 ;
181/199; 381/338 |
International
Class: |
H05K 005/00; H04R
001/20 |
Foreign Application Data
Date |
Code |
Application Number |
May 25, 2000 |
DK |
PA 2000 00834 |
Claims
1. Acoustic transmission connection comprising a tubular element in
which speech signals can be transmitted from a first end of the
tubular element to a second end of the tubular element, and a
transducer which is placed in the proximity of the second end of
the tubular element, so that speech signals which are transmitted
from the first end to the second end of the tubular element are
converted to electrical signals by the transducer, and where the
transducer is placed in a housing in a first cavity which stands in
connection with the second end of the tubular element via an
acoustic channel, and that in connection with the said second end
of the tubular element, means are configured for acoustic impedance
matching of the transmitted signals, said means for acoustic
impedance matching comprising a further acoustic channel, which
from the said second end of the tubular element leads to a second
cavity in the housing, characterized in that in the housing an
element is configured in which the first-mentioned and the further
acoustic channel are formed, and that this element is placed
between the transducer and the second end of the tubular
element.
2. Acoustic transmission connection according to claim 1,
characterized in that the further acoustic channel comprises two or
more part-channels, each of which leads from the second end of the
tubular element to the second cavity.
3. Acoustic transmission connection according to one or more of the
claims 1-2, characterized in that the connection comprises a
further tubular element which is placed extending in substantially
the same direction as the first-mentioned tubular element, in that
the further tubular element similarly has a first and a second end,
where the second end stands in connection with a transducer in the
housing.
4. Acoustic transmission connection according to claim 3,
characterized in that the second end of the further tubular element
is similarly connected to means for acoustic impedance matching,
said means comprising an acoustic channel which leads from the
second end of the further tubular element to a third cavity in the
housing.
5. Headset comprising a transducer for conversion of speech signals
to electrical signals, which transducer is placed in an
encapsulation, and a tubular element which has a first end and a
second end, where the first end is arranged to receive speech
signals, mainly from a user's mouth, where the second end stands in
connection with the transducer, and where the speech signals are
transmitted via the tubular element to the transducer, and where
the transducer is placed in the encapsulation in a first cavity
which stands in connection with the second end of the tubular
element via an acoustic channel, and that in connection with the
said second end of the tubular element, means are configured for
acoustic impedance matching of the transmitted signals, said means
for acoustic impedance matching comprising a further acoustic
channel, which from the said second end of the tubular element
leads to a second cavity in the encapsulation, characterized in
that in the encapsulation an element is configured in which the
first-mentioned and the further acoustic channel are formed, and
that this element is placed between the transducer and the second
end of the tubular element.
6. Headset according to claim 5, characterized in that the further
acoustic channel comprises two or more part-channels, each of which
leads from the second end of the tubular element to the second
cavity.
7. Headset according to one or more of the claims 5-6,
characterized in that the connection comprises a further tubular
element which is placed extending substantially in the same
direction as the first-mentioned tubular element, in that the
further tubular element similarly has a first and a second end,
where the second end stands in connection with a transducer in the
encapsulation.
8. Headset according to claim 7, characterized in that the second
end of the further tubular element is similarly connected to means
for acoustic impedance matching, said means comprising an acoustic
channel which leads from the second end of the further tubular
element to a third cavity in the encapsulation.
9. Use of an acoustic transmission connection according to one or
more of the claims 1-4 in connection with a hearing aid or for
audiological measurements for adjustment of the hearing aid to the
user.
10. Use of an acoustic transmission connection according to one or
more of the claims 1-4 in connection with a microphone, chiefly in
connection with a directionally determined microphone.
11. Use according to claim 10 in connection with a probe
microphone.
12. Use according to claim 10 in connection with a microphone
array.
Description
[0001] The invention concerns an acoustic transmission connection
which comprises a tubular element in which speech signals can be
transmitted from a first end of the tubular element to a second end
of the tubular element, and a transducer which is placed in the
proximity of the second end of the tubular element, so that speech
signals which are transmitted from the first end to the second end
of the tubular element are converted to electrical signals by the
transducer. The invention also comprises a headset of the kind
disclosed in the preamble to claim 7.
[0002] With headsets and ear-hook headsets, use is most often made
of a small microphone, which is placed at the end of an elongated
and possibly flexible element, so that the microphone is placed in
the proximity of the user's mouth when the user is wearing the
headset.
[0003] It is also known, however, that use can be made of a voice
tube, also known as a sound tube or the like, and which consists
substantially of a tubular element, a sound tube, with its one end
in the proximity of the user's mouth and the other end mounted in
the headset, so that the speech signals transmitted by the tube are
fed forward to a microphone.
[0004] Such a headset is known, for example, from U.S. Pat. No.
5,761,298. With such an arrangement, among other things the
advantage is achieved that the relatively heavy and space-demanding
microphone does not need to be placed at the end of the relatively
weak, elongated element, and thus not be of inconvenience to the
user in this place. A disadvantage with the use of voice tubes is
that the occurrence of standing waves in the tube must be avoided,
which in this known technique is aimed at by using an acoustic
filter at the free end of the tube. However, other disadvantages
arise hereby, in that such a filter which, for example, can be
configured of damping material, steel wool or the like, will damp
the speech signal so that the sensitivity of the overall microphone
arrangement is reduced. Moreover, with time the filter will collect
dust particles and other impurities, so that an even greater
damping of the sound will take place.
[0005] From German publication no. 1.098.999, a headset is known
where in the one side a transducer is placed, which is used as both
speaker and microphone, and where a sound tube is led to the
transducer's encapsulation. From the space in the encapsulation
there is a small opening out towards the user's ear, whereby a
certain damping of high-frequency noise signals can be achieved.
Normally, it is not desirable to use the same transducer both as
speaker and microphone, even though a reduction in weight can be
obtained, the reason being that an adequate acoustic quality cannot
be achieved. Moreover, the construction shown does not have means
for the damping of standing waves in the sound tube if the inlet
part of the sound tube does not comprise filter means or the
like.
[0006] It is thus an object of the invention to provide a solution
to these problems, so that the use of an acoustic filter at the
free end of a voice tube can be avoided, while at the same time a
satisfactory transfer of the speech signals to the microphone is
ensured.
[0007] This is achieved by configuring the acoustic transmission
connection as disclosed and characterised in claim 1, e.g. in
connection with a headset as disclosed and characterised in claim
7. The possibility is hereby provided of effecting an acoustic
adjustment, so that standing waves in the sound tube are avoided,
and so that desired acoustic characteristics are obtained depending
on the purpose for which the acoustic transmission connection is to
be used. If a headset is involved, e.g. for telephonic use or the
like, it is possible to achieve acoustic characteristics which can
be converted to electrical signals which provide a particularly
good telephone transmission quality.
[0008] By configuring the invention as disclosed and characterised
in more detail in the claims 2, 3, 4 or 8, 9 or 10, in a simple
manner the possibility is provided of realising desired acoustic
characteristics in practice. This is effected in a way and with
means, which, in a simple and herewith relatively cheap manner, can
be manufactured and mass-produced. The simple construction also has
the result that this can be a mechanically stable and durable
construction, so that no changes arise in characteristics even
after long-time use.
[0009] If the acoustic transmission connection according to the
invention is configured as disclosed and characterised in claim 5,
e.g. in connection with a headset as disclosed and characterised in
claim 10, acoustic directivity is introduced, in that the
sensitivity becomes direction dependent. This provides the
possibility of adjusting the acoustic transmission connection more
precisely for a given use. If it is to be used for a microphone,
e.g. a headset, it is possible to achieve desired noise
suppression, or it can be achieved that mainly only sound from
certain directions is detected. Such acoustic qualities have very
great practical significance. These characteristics and advantages
can be improved further by configuring the transmission connection
according to the invention as disclosed and characterised in claim
6, e.g. in connection with a headset as disclosed and characterised
in claim 11 or 12.
[0010] As will also be seen from the explanation in the
description, an acoustic transmission connection according to the
invention has a great practical advantage when used as disclosed in
more detail in the claims 13-16.
[0011] In the following, the invention will be explained in more
detail with reference to the drawings, where
[0012] FIG. 1 shows a headset with an acoustic transmission
connection according to the invention,
[0013] FIG. 2 shows on a larger scale a plane section in the
microphone boom in the headset in FIG. 1, said boom comprising the
acoustic transmission connection,
[0014] FIG. 3 shows on an even larger scale and in partly separated
form a first embodiment of an acoustic transmission connection
according to the invention,
[0015] FIG. 4 shows an electrical equivalent diagram, which
corresponds to an acoustic transmission connection as shown in
FIGS. 2 and 3,
[0016] FIG. 5 shows in partly separated form a second embodiment of
an acoustic transmission connection according to the invention,
[0017] FIG. 6 shows a side view, on a larger scale, of the
embodiment of the invention shown in FIG. 5,
[0018] FIG. 7 shows parts of the embodiment shown in FIG. 3, seen
in perspective and on an even larger scale,
[0019] FIG. 8 shows the parts shown in FIG. 5, but in another
perspective,
[0020] FIG. 9 shows a side view of a longitudinal section through
the embodiment shown in FIGS. 5-8, but in assembled state,
[0021] FIG. 10 shows a frequency characteristic for an acoustic
transmission connection according to the first embodiment of the
invention,
[0022] FIG. 11 shows frequency characteristics for an acoustic
transmission connection according to the second embodiment of the
invention,
[0023] FIG. 12 similarly shows frequency characteristics for the
second embodiment,
[0024] FIG. 13 shows space characteristics for the second
embodiment according to the invention, and
[0025] FIG. 14 shows on another scale an embodiment of the
invention comprising a microphone housing, two sound tubes and a
termination part as one unit.
[0026] In FIG. 1 is seen an example of a complete headset 13 in
which use can be made of the acoustic transmission connection 1
according to the invention. The transmission connection 1 comprises
a tubular element 2 and a housing 3, which parts will be discussed
in more detail later. Additionally, the headset has a housing part
15 which forms a mechanical transition between the microphone boom
and the housing 14, in which is placed a transducer in the form of
a telephone capsule or the like. The housing parts 14 and 15 can be
turned in relation to each other.
[0027] In FIG. 2 a plane section through the microphone boom itself
is seen, and in addition to what is seen in FIG. 1, a speaker or
microphone 4 and an adjustment element 7 are shown, which form part
of the acoustic transmission connection, and which therefore are
discussed in more detail later. At the free end of the tubular
element 2 a termination part 16 is seen, which constitutes the
sound inlet, and which can possibly comprise an acoustic
filter.
[0028] FIG. 3 shows the parts, which form a first embodiment 1 of
an acoustic transmission connection according to the invention,
which for example can be used in connection with a headset. 2
indicates the tubular element, which in the following is called the
sound tube, and which serves to lead audio signals from its one
end, which for example can be in the proximity of the user's mouth,
to the other end, which is suspended in a housing 3.
[0029] This housing 3 consists of two half-parts 3a and 3b, and
among other things serves to secure a transducer 4 for the
conversion of speech signals to electrical signals. In the
following, this transducer will also be referred to as the
microphone. The sound tube 2 is secured in the one half-part 3a of
the housing and stands in connection with a conical cavity 5 via a
short tube connection 6. The conical cavity 5 is designed to
accommodate a correspondingly conical element 7, which has a
through-going acoustic channel 8, e.g. in the form of a hole
extending substantially along its axis. The element 7 also has one
or more additional acoustic channels 9, which can be configured as
grooves or slots, which extend in the surface of the element 7
substantially in the longitudinal direction of the element. For
example, the element 7 can be configured with four slots 9 which
are displaced by 90.degree. from one another along the surface of
the element 7. As will be seen in FIG. 3, when the element 7 is
placed in the cavity 5, the channel 8 will form a continuation of
the connection from the sound tube 2, and the further acoustic
channel(s) 9, which outwardly are closed by the inner surface of
the cavity 5, will function as connection from the sound tube 2 and
forward to the rear end and outer edge of the element 7. These
acoustic channels 9 terminate in an annular area 17 along the end
surface of the element 7 at that end which is arranged to face
inwards towards the microphone 4. The channels 9 are connected to
one another by the annular area.
[0030] When the element 7 is placed in the cavity 5, the microphone
4 can be placed in the space 10 in the half-part 3a. Between the
element 7 and the microphone 4, two volumes are hereby formed, i.e.
a volume opposite the acoustic channel 8, which serves to transfer
speech signals to the transducer 4 itself, and a volume comprising
the annular area 17 along the periphery of the transducer 4 and the
element 7, which volume is connected to the acoustic channel(s) 9,
in that this volume and the channels 9 serve as impedance matching
for the whole of the acoustic system. This will be described in
more detail later in connection with FIG. 4.
[0031] The housing half-part 3a is provided in the space 10 with
internal locking elements 11a, which can co-operate with external
locking elements 11b on the housing half-part 3b, so that the two
half-parts are held together. The locking elements can, for
example, be annular snap-lock parts. On the housing half-part 3b
there is a connection part 12, which serves to connect the part 1,
for example, to the remaining part of a headset. Finally, at the
first end (not shown) of the sound tube 2, a resistive damping
arrangement in the form of an acoustic filter can be provided, said
arrangement consisting, for example, of damping material, steel
wool or the like, which can serve as supplement to the built-in
impedance matching which consists of the acoustic channel(s) 9 and
the connected volume.
[0032] The sound tube 2 can be configured in a material, which
allows the tube to be bent, especially so that the tube continues
to assume the shape it is given. This is expedient in connection
with a headset, for example, where the first end of the sound tube
can be adjusted individually by the user and brought into the
proximity of the mouth as required.
[0033] FIG. 4 shows the equivalent electrical diagram, which
corresponds to the acoustic system, which is described above. Here,
20 indicates the generator, which corresponds to the sound source,
which transmits sound through the air. The resistance of the air is
indicated at 21, and the resistance of a possibly used resistive
damping at the first end of the sound tube is indicated at 22. The
sound tube 2 itself and the equivalent impedance of the short tube
connection 6, which is resistive, are indicated at 23 and, as shown
earlier, the sound tube is coupled to the acoustic channel 8, which
has the equivalent resistance 26, and to the acoustic channel(s) 9
with the equivalent resistance 24, which in turn is coupled to an
equivalent capacitance 25, corresponding to the terminating volume
which comprises the annular area 17. From the equivalent resistance
26, the signal is coupled to a resistance 27 and an inductance 28,
which represents the microphone 4, and a capacitance 29, which
represents the space in which the microphone is placed. The
resulting signal can thus be taken off at the node 30, and it is
seen that by the calculation methods normally used in connection
with electrical circuits, the values can be calculated for the
resistance 24 and the capacitance 25 which will provide a suitably
even transfer function for the acoustic circuit and forward until
the electrical signal is taken off at 30. When the other values in
the circuit are known, these values can be used in the dimensioning
of the acoustic channel(s) 9 and the volume associated herewith,
and/or an iterative calculation process can be carried out, in that
other values forming part of the circuit can be changed, such as
e.g. the resistance 26 corresponding to the acoustic channel 8.
[0034] FIGS. 5-9 show details of a second embodiment of the
invention, where use is made of the same principle in the
configuration of an acoustic transmission connection, but where two
substantially identical transmission connections are coupled
together in parallel, or substantially in parallel, in that a minor
angular difference can be involved, whereby directivity for the
connection can be obtained.
[0035] Such an acoustic transmission connection 40 is shown in FIG.
5, where the most important of the individual parts are shown
separated from one another. As will be seen, the connection
comprises two identical sound tubes 42, each with a first end 42a
and a second end 42b. These sound tubes are each mounted in an end
part of their separate housings 43, which also contain cavities,
which can be. blocked off with plugs 45 in the sides and plugs 46
in the other end parts of the housings 43. The two housings can be
joined together, in that between them they secure a transducer 44,
and in that studs 47 and corresponding stud holes 48 are provided
in the two surfaces, which are brought together for mutual
positioning and securing. As will be seen, with the shown
positioning of the studs 47 and stud holes 48, the two housings can
be configured in an identical manner.
[0036] As will be seen in FIGS. 6 and 7, where FIG. 7 shows only
the one housing 43 With associated parts, in the one end part of
the housings 43 cylindrical openings or holes 50 are configured,
which serve to accommodate the end parts 42b of the sound tubes 42.
Moreover, cylindrical openings or holes 49 in which the plugs 45
are placed are configured from the side. Finally, from the other
end parts of the housings 43 cylindrical openings or holes 51 are
configured which, as shown, can be plugged with the plugs 46. As
will be seen, the holes 50, 49 and 51 adjoin one another, so that
there is free passage between the respective holes before the plugs
45 are placed in the holes 49.
[0037] In FIG. 7 and FIG. 8 it is shown how at the innermost end of
each plug 45 an annular undercut or step or the like 56 is
provided, which extends all the way around the end part of the
plug. Moreover, from the one side a radial slot 57 is configured,
which extends substantially in to the center axis of the plug
45.
[0038] It is also seen from FIGS. 7 and 8 that holes 52 are
provided in each side of the transducer 44, in that these holes
serve to lead speech signals in to the active part of the
transducer part, e.g. a membrane or the like, and that the.
transducer has terminals 53 for the electrical connection at its
end. The transducer is received in recesses 54 in the housings 43,
and in extension of these recesses there are channel-shaped
recesses 55 for e.g. cable connections. Finally, it is seen in
FIGS. 7 and 8 that each side of the transverse hole 49 is
configured with recesses 58, the function of which will be
described in more detail in the following with reference to FIG. 9,
which shows a longitudinal section of the assembled acoustic
transmission connection.
[0039] When each sound tube 42 is placed with its second end part
42b in the corresponding bore 50, the speech signals can pass from
each sound tube forward to the foremost recesses 58. From here, the
speech signals can pass either via the radial slot 57 to the hole
52 in the transducer 44, which corresponds to the first acoustic
channel 8 in the first embodiment according to the invention, or
the speech signals can pass via the annular undercut 56 and
rearwards to the cavity in the bore 51, which as mentioned is
closed with the plug 46. This latter connection corresponds to the
additional acoustic channel(s) 9 which are described in connection
with the first embodiment of the invention. An acoustic system
which is similar to that described in connection with the
embodiment shown in FIG. 3 is hereby established, and thus an
acoustic impedance matching can be established in the same manner
as explained earlier, e.g. by dimensioning and configuration of the
recesses 58, the slots 57 and the undercuts. 56 so that a desired
frequency response is achieved.
[0040] With this embodiment, where two substantially identical
transmission connections are coupled in parallel, a directional
effect can also be achieved. In that the incoming speech signals
will influence the same transducer, but from each their side,
signals which arrive from the same direction will have a phase
difference which is dependent on the angle which the incoming
speech signals form with the axis of the sound tubes. 42. Speech
signals which come in with the same direction as the axes of the
sound tubes, when it is presupposed that the other or free ends 42a
of the sound tubes end at the same place in the longitudinal
direction, will reach forward to the transducer with the same
phase, whereby the two speech signals which influence each their
side of a membrane or corresponding, movable element in the
transducer 44, will equalise each other. On the other hand, if an
angular difference is involved, a phase difference will arise at
the transducer depending on the size of the angular difference, so
that the resulting electrical signal will be dependent on the
direction of the received speech signals. If the free ends 42b of
the sound tubes do not end at the same place in the longitudinal
direction, this will naturally have an influence on which direction
will now be that which provides an equalisation of the two incoming
signals.
[0041] FIG. 10 shows the frequency characteristic for an acoustic
transmission connection such as that e.g. described in connection
with FIGS. 3 and 4, in that it has been recorded for a sound tube
with an external diameter of 2.0 mm and an internal diameter of 0.7
mm. As will be seen, no significant resonance areas arise in the
characteristic, which over a wide frequency range remains within an
area of 5 dB. In FIG. 10 the limits for what can normally be
considered as an acceptable frequency range for the recording of
sound for ordinary communication, e.g. telephone communication, are
also drawn. It is seen that the frequency characteristic remains
entirely within these limits.
[0042] In FIGS. 11, 12 and 13 are shown space characteristics for a
transmission connection of the kind, which is described in
connection with FIGS. 5-9. FIG. 11 shows frequency characteristics
for 0.degree. and 90.degree., respectively, from which it is seen
that there is a distinct difference in the levels for the received
signals. The acoustic . transmission connection is thus
directionally dependent.
[0043] FIG. 12 correspondingly shows characteristics for an
acoustic transmission connection where recordings for 0.degree.,
400.degree., 900.degree. and 150.degree. have been made. Finally,
FIG. 13 shows the spatial characteristic for the frequencies 500 Hz
1000 Hz, 2000 Hz and 3000 Hz. Also here a directional dependence is
ascertained.
[0044] A transmission connection of the type described above in
connection with FIGS. 5-9 can expediently be used in connection
with a headset, in that the two tubes can thus be molded into a
protective and positioning layer of e.g. plastic, or enclosed
within a similar protective layer so that the sound tubes appear as
a single element. The directivity will hereby result in the sound
from a users mouth being predominant in relation to other sounds,
such as noise from the surroundings, speech from other persons etc.
A significant improvement in the comprehensibility and clarity of
the recorded sound is hereby achieved.
[0045] FIG. 14 shows a section through a microphone arm
corresponding to that shown in FIG. 2, but configured as a
one-piece unit, e.g. injection moulded in plastic. The unit
comprises the microphone housing 3 with microphone 4 and wires 18
hereto, two sound tubes 2 and a terminating part 16, so that two
sound inlet openings 17a and 17b are provided, one for each sound
tube 2.
[0046] This configuration, which is shown only in a principle
drawing, shows a practical embodiment for a unit which can be
arranged for coupling together with e.g. a telephone housing 14 as
in FIG. 1 for the formation of a headset. The detailed
configuration of the microphone housing 3 is not shown in FIG. 14,
but the housing 3 can be configured so that it can be coupled in a
simple manner with e.g. a headband and a telephone housing for a
headset, which can be adjusted individually by the user.
[0047] Furthermore, the described embodiments of the invention can
be used in other connections, where speech signals are to be
registered or transmitted in a place to which accessibility can
possibly be difficult, and where the transducer itself is placed at
a certain distance from the place where the speech signals are
registered or recorded. For example, this can be the case in
connection with hearing aids and in connection with probe
microphones. Probe microphones are used, for example, to register
speech signals in a person's ear, e.g. in the auditory canal, which
is of significance in the adjustment of hearing aids where it is
desired to register those signals which are actually transmitted
further into the user's ear.
[0048] Moreover, the acoustic transmission connection can be used
in connection with microphone arrays which are configured with
regard to a certain directional characteristic, e.g. a very narrow
directional characteristic which, for example, is desirable in
connection with microphones for use at conferences, the use of PCs
etc., where it is only the speech signals from a single person
among many which are desired to be detected by the microphone. For
such a use, the embodiment which is described in connection with
FIGS. 5-9 will be expedient, in that the directional characteristic
of this in connection with the configuration of the microphone in
an array will prove further directional determination when the
received signals are summated, such as is known from microphone
arrays, possibly combined with electrical signal processing of the
received signals for amplification of the directivity, such as is
also commonly known in connection with microphone arrays.
* * * * *